Sydney
Water accounting policies

The information presented in the Sydney region is based on agreements between the Bureau of Meteorology (the Bureau) and reporting partners, including:

• New South Wales Office of Water
• Sydney Catchment Authority
• Sydney Water Corporation
• Shoalhaven City Council
• Wingecarribee Shire Council
• Goulburn Mulwaree Council
• Lithgow City Council
• Delta Electricity.

The report has been prepared using an accrual basis of water accounting, with the exception of the physical water flow information. The water attribute being quantified is volume and the unit of account is litres presented as megalitres (ML).

Only water that is held or managed by the state licensing authority, the region's irrigation scheme or the urban water system, and from which future benefit can be derived by stakeholders of the region, is defined as a water asset. Water liabilities are constituted by present commitments to supply water, the discharge of which is expected to result in a decrease of the region's water assets or an increase in another water commitment to supply water.

A water asset is recognised in the Statement of water assets and water liabilities providing:

• its volume can be quantified in a way that is complete, neutral and free from material error, and
• the derived benefit is probable.

A water liability is recognised in the Statement of water assets and water liabilities providing:

• its volume can be quantified in a way that is complete, neutral and free from material error, and
• the decrease of the region' water assets or increase in another water commitment to supply water is probable.

Water held in off-channel storages that has already been abstracted from the entitlement system is deemed not to be part of the region (regardless of the storage's size or connection to the system). This is because the attendant water right has already been exercised. 

Line item 1.2 Unregulated river is recognised as a water asset for the channel reaches for which reliable data are available to quantify the volume in a way that is complete, neutral and free from material error.

Although water within line item 1.3 Regulated river is a vital water asset for the conveyance of water within the water report entity, it cannot be quantified in a way that is complete, neutral and free from material error because reliable data are not available. The omission of this volume from the water accounting statements is not considered to have a material impact.

The volume of water within line item 1.4 Lakes and wetlands cannot be quantified in a way that is complete, neutral and free from material error because reliable data are not available. The volume of water held in lakes and wetland is relatively small in size and its omission does not have a material impact on the total water resource available. It is recognised that water within Line item 1.4 makes a significant contribution to environment benefits in the water report entity.

Line item 2.1 Groundwater within the Sydney region cannot be quantified in a way that is complete, neutral and free from material error because reliable data are not available. Information in relation to groundwater is recorded in Contextual information, at the end of this note (Water assets and liabilities that fail the recognition criteria) and in the note Water rights, entitlements, allocations and restrictions.

The water within 3 Urban system cannot be quantified in a way that is complete, neutral and free from material error because reliable data are not available and, as such, it is not recognised in the Statement of water assets and water liabilities. This is the case for line item 3.1, line item 3.2 and line item 3.3. It is considered that the pipes are always full and may hold a large volume of water, but the omission of the volume from the Statement of water assets and water liabilities is not considered material because the volume is nearly the same throughout the year.

 

The increases and decreases to the water assets and water liabilities reported consist only of changes that can be quantified in a way that is complete, neutral and free from material error. These volumes are reported in the Statement of changes in water assets and water liabilities or the Statement of physical water flows.

Precipitation and evaporation (line item 9.1 Precipitation on surface water and line item 17.1 Evaporation from surface water) are only recognised in relation to storage surfaces and unregulated river channels for which volumes are provided in the water accounting statements. It does not represent all precipitation and evaporation within the physical region of the water report entity. Notably, these processes occurring from the landscape are not captured.

The portion of runoff that flows into the surface water store (storages and rivers) is quantified and recognised in the water accounting statements. This runoff includes precipitation captured in the catchment less landscape evaporation and is recorded as line item 9.4 Runoff to surface water.

The volumes of several water assets and water liabilities identified in the Sydney region were not recognised in the water accounting statements but replaced by dashes ('–') because they failed the recognition criteria specified in the Exposure Draft of the Australian Water Accounting Standards 1, as:

• they could not be quantified in a way that is complete, neutral and free from material error, or
• in the case of water assets, they were unlikely to provide a future benefit to the region or the region's stakeholders
• in the case of water liabilities, they were unlikely to result in a decrease in the region's water assets or an increase in another water liability when the obligation is discharged.

The description of those water assets and water liabilities that failed the recognition criteria is given in the following line item notes:

1.4 Lakes and wetlands

2.1 Water table aquifer

3.1 Urban water supply system

3.2 Wastewater collection system

3.3 Recycled water supply system

The volumes of several changes to water assets and water liabilities identified in the Sydney region were not reported in the water accounting statements but replaced by dashes ('–') because they could not be quantified in a way that is complete, neutral and free from material error.

• they could not be quantified in a way that is complete, neutral and free from material error, or
• in the case of changes to water assets, they were unlikely to provide a future benefit to the region or the region's stakeholders
• in the case of changes to water liabilities, they were unlikely to result in a decrease in the region's water assets or an increase in another water liability when the obligation is discharged.
  

The description of those changes to water assets and water liabilities that failed the recognition criteria is given in the following line item notes:

 

9.6 Overbank flood return to river channel

10.1 Groundwater inflow from outside region

10.2 Groundwater inflow from outside region at coast

10.3 Recharge from landscape

17.5 Overbank flood spilling

18.1 Groundwater outflow to outside region

18.2 Groundwater outflow to outside region at coast

18.3 Discharge to landscape.

Several comparative year volumes in the water accounting statements were restated from the 2010 Account in order to provide more useful information to the users. Restatements may be due to either of the following causes:

• change in the presentation of the water accounting statements, which line items were generally simplified since the 2010 Account
• change in scope, for instance to include more of the region's area in the definition of a line item in order to present more complete information
• improvement in quantification methodology
• increase in the data available to quantify a line item.

In accordance with the Exposure Draft of the Australian Water Accounting Standards 1, (the Standards), changes of presentation and scope of the line items led to an automatic restatement of the values in the water accounting statements. Changes of methodologies and data availability, although not required by the Standards, led to a restatement of the volumes in the water accounting statements if the change was considered material. In particular, any change affecting the allocation accounts was restated.

The notes attached to the line items of the water accounting statements give the detail on all the restatements made.

In the 2010 Account, internal transactions between various water assets and water liabilities of the region were reported in the water accounting statements. In the 2011 Account, these internal transactions were not reported in the water accounting statements for the following reasons:

• they did not affect the region's total water assets and water liabilities,

• feedback was received that presenting these internal transactions in the water accounting statements was confusing, as the same water appeared in the water accounting statements as both a claim to water and an obligation to deliver water and as both an inflows and an outflows in relation to the various water assets and water liabilities.

  
  

In the 2011 Account, these internal transactions are reported instead in the Resources and systems suite of notes: Surface water and System's interactions with the region.